I Have had the vita since launch. I had a fully hacked PSP slim and it was nice to have until i needed quick cash. after waiting months and months for great content to come out. I'm not gonna lie here Gravity rush is a great quick game with not much replay value to me. Ragnarok Odyssey is the must have game right now and even it get's old fast. My favorite purchase sofar has been metal gear HD package with Metal gear 2 & 3 two fully epic games upgraded to hd they look fantastic on the oled screen. recently I picked up a PSP GO and a PS3 controller for $100 with the digital collection i had of games on playstation network it was worth it to replace. here's my take for you based on all that.

If you have the cash to get a Vita and say 2 or 3 new games and a memory card (I spent about $600 total so far on my vita.) then you could afford a PSP and a much larger collection of games.

PS Vita all the way, while the selection is a bit small, the games I've owned so far are simply sublime. And the apps work on par with their android/iOS counterparts, apart from Skype. That's still pretty terrible on the Vita sadly.

PS Vita, there some awesome games on it, and you can easily download PSP games off the store. I suggest getting a PS+ subcription, you'll get tons of free PSP games like all the Resident Evil's on PS1.